Objective To assess the value of blood oxygen level-dependent magnetic resonance imaging (BOLD-MRI) in diagnosis and prediction of early acute renal transplant rejection. Methods BOLD-MRI was performed in a cohort of 103 patients undergoing cadaver renal transplantation between Dec 2005 and March 2007. Among them, 82 recipients had normal renal function, 21 had biopsy-proved acute rejection. R2* (1/s) measurements were obtained in the medulla and cortex of grafted kidneys. Results R2* values of the medulla were significantly lower in the acute rejection group [R2*=(14.02±2.68)/s] than that in the normally functioning transplants group [R2*=(16.66±2.82)/s], the difference between these two groups was significant (P<0.01); ROC curve analyses suggested that medullary MR2* values could accurately identify acute rejection in the early post-transplantation period. In the normal functioning transplant group, those with lower medullary R2* values (MR2*<14.9/s, n=23) had higher acute rejection rates than those with higher medullary R2* values (MR2*>14.9/s, n=59) in the first 6 months following transplantation, but the difference between these two groups was not significant (17.39％ vs 8.47％, P=0.259). Conclusions Mean R2* values in the medullary regions of grafted kidneys with BOLD-MRI may be a non-invasive diadynamic criteria with good sensitivity and specificity, and may be a valuable predictor of early acute renal transplant rejection.